Fig. 9. Cholinergic neurons from the basal magnocellular complex are displaced in the midline of Slit1;Slit2 double mutants. Coronal sections through the telencephalon of newborn fetuses showing choline acetyltransferase (ChAT) immunohistochemistry in wild-type (A,C,D,G,H) and Slit1;Slit2 mutant (B,E,F,I,J) mice. (A,B) Distribution of cholinergic cells at the level of the anterior commissure in wild-type (A) and Slit1;Slit2 mutant (B) mice. In the preoptic area, note the collection of ectopic cholinergic neurons close to the midline, where some cells and fibers cross the midline in Slit1;Slit2 mutant mice (arrow in B). Ectopic cells appear to be continuous with other cholinergic neurons in the basal magnocellular complex (arrowhead). Additional ectopic cells are present in the anterior commissure (open arrowhead). (C,D,E,F,G,I) High magnification the boxed areas in A and B. (H,J) High magnification photographs of the basal magnocellular complex at caudal levels in wild-type (H) and Slit1;Slit2 mutants (J). Dashed lines in C and E indicate the midline. ac, anterior commissure; BMC, basal magnocellular complex; GP, globus pallidus; PCx, piriform cortex; POa, preoptic area; Str, striatum; Scale bars: 300 µm (A,B); 100 µm (C-J).